THE ROLE OF GAP JUNCTION MEMBRANE CHANNELS IN DEVELOPMENT

In most developmental systems, gap junction mediated cell-cell communi cation (GJC) can be detected from very early stages of embryogenesis. This usually results in the entire embryo becoming linked as a syncyti um. However, as development progresses, GJC becomes restricted at disc rete boundaries, leading to the subdivision of the embryo into communi cation compartment domains. Analysis of gap junction gene expression s uggests that this functional subdivision of GJC may be mediated by the differential expression of the connexin gene family. The temporal-spa tial pattern of connexin gene expression during mouse embryogenesis is highly suggestive of a role for gap junctions in inductive interactio ns, being regionally restricted in distinct developmentally significan t domains. Using reverse genetic approaches to manipulate connexin gen e function, direct evidence has been obtained for the connexin 43 (Cx4 3) gap junction gene playing a role in mammalian development. The chal lenges in the future are the identification of the target cell populat ions and the cell signaling processes in which Cx43-mediated cell-cell interactions are critically required in mammalian development. Our pr eliminary observations suggest that neural crest cells may be one such cell population.